Issue 63

G. Santosh et alii, Frattura ed Integrità Strutturale, 63 (2023) 100-109; DOI: 10.3221/IGF-ESIS.63.10

Rockwell ball hardness tests were performed to study hardness properties of prepared samples as per ASTM E18-20 standard and optical microscopy was used to study microstructural characteristics and to examine uniform distribution of particles in matrix alloy. Finally, scanning electron microscopy (SEM) images of failed specimens were analyzed to study their fracture behavior.

R ESULTS AND DISCUSSION

Microstructural characterization he rare earth compounds viz. Y 2 O 3 and CeO 2 were incorporated into AZ91D Mg alloy in the current work. Microstructure of prepared samples of MMCs were studied through optical microscopy as illustrated in Fig. 3 (a) – (d). The microstructure of alloy and MMCs revealed the dispersion of β -phase in α -phase and nearly uniform distribution of particulates in the matrix. Further, pure matrix alloy illustrates large grain structure and intermetallic formation at the interface. Fig. 3(b) depicts that addition of 1% Y 2 O 3 and 1% CeO 2 has refined the grain structure. While the refinement of grain structure enhanced with the increase in the percentage of Y 2 O 3 , which can be found in Fig. 3(c) and Fig. 3(d). Also, coarse structure present in the pure alloy has been broken and formed dentritic structure in the 1% Y 2 O 3 +1% CeO 2 incorporated MMCs. It was further enhanced with 3% Y 2 O 3 +1% CeO 2 reinforcement in the alloy. Fig 3(c) reveals the dentritic skeleton structure occurrence in the α -phase of MMC with fine and smooth microstructure. Fig. 3(d) shows the further refinement of α -phase, but simultaneously dispersion of β -phase has increased to greater extent. The β -phase increase has resulted in the better interconnected intermetallic compound. Also, Similar results were found in the earlier literature elsewhere for Y 2 O 3 /Mg MMC [24-29]. T

Figure 3: Microstructure of (a) AZ91D Magnesium Alloy; (b) AZ91D+1%Y 2 O 3 +1%CeO 2 ; (c) AZ91D+2%Y 2 O 3 +1%CeO 2 ; (d) AZ91D+3%Y 2 O 3 +1%CeO 2 hybrid composites.

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